select f1,f2 from table1,table2 where table1.id=table2.id
与
select f1 from table1
join
select f2 from table2
on table1.id=table2.id这两条语句性能上有没有什么区别?
与
select f1 from table1
join
select f2 from table2
on table1.id=table2.id这两条语句性能上有没有什么区别?
select f1,f2 from table1,table2 where table1.id=table2.id
与
select f1,f2 from table1 a
join table2 b
on a.id=b.id
我也是菜鸟,只提个意思而已